scholarly journals A new index for the interplanetary merging electric field and geomagnetic activity: Application of the unified polar cap indices

Space Weather ◽  
2007 ◽  
Vol 5 (9) ◽  
pp. n/a-n/a ◽  
Author(s):  
Peter Stauning
Keyword(s):  
Electric Field ◽  
Geomagnetic Activity ◽  
Polar Cap

Solar and Geomagnetic Activity Impact on Occurrence and Spatial Size of Cold and Hot Polar Cap Patches

2021 ◽  
Author(s):  
Duan Zhang ◽  
Qing He Zhang ◽  
Y. Z. Ma ◽  
Kjellmar Oksavik ◽  
L. R. Lyons ◽  
...  
Keyword(s):  
Geomagnetic Activity ◽  
Polar Cap ◽  
Spatial Size

scholarly journals A multi-satellite study of accelerated ionospheric ion beams above the polar cap

2006 ◽  
Vol 24 (6) ◽  
pp. 1665-1684 ◽  
Author(s):  
R. Maggiolo ◽  
J. A. Sauvaud ◽  
D. Fontaine ◽  
A. Teste ◽  
E. Grigorenko ◽  
...  
Keyword(s):  
Electric Field ◽  
Potential Drop ◽  
Auroral Zone ◽  
Ion Beams ◽  
Distribution Functions ◽  
Convection Velocity ◽  
Polar Cap ◽  
Ion Energy ◽  
Polar Cusp ◽  
Oxygen Ions

Abstract. This paper presents a study of nearly field-aligned outflowing ion beams observed on the Cluster satellites over the polar cap. Data are taken at geocentric radial distances of the order of 5–9 RE. The distinction is made between ion beams originating from the polar cusp/cleft and beams accelerated almost along the magnetic field line passing by the spacecraft. Polar cusp beams are characterized by nearly field-aligned proton and oxygen ions with an energy ratio EO+ / EH+, of the order of 3 to 4, due to the ion energy repartition inside the source and to the latitudinal extension of the source. Rapid variations in the outflowing ion energy are linked with pulses/modifications of the convection electric field. Cluster data allow one to show that these perturbations of the convection velocity and the associated ion structures propagate at the convection velocity. In contrast, polar cap local ion beams are characterized by field-aligned proton and oxygen ions with similar energies. These beams show the typical inverted V structures usually observed in the auroral zone and are associated with a quasi-static converging electric field indicative of a field-aligned electric field. The field-aligned potential drop fits well the ion energy profile. The simultaneous observation of precipitating electrons and upflowing ions of similar energies at the Cluster orbit indicates that the spacecraft are crossing the mid-altitude part of the acceleration region. In the polar cap, the parallel electric field can thus extend to altitudes higher than 5 Earth radii. A detailed analysis of the distribution functions shows that the ions are heated during their parallel acceleration and that energy is exchanged between H+ and O+. Furthermore, intense electrostatic waves are observed simultaneously. These observations could be due to an ion-ion two-stream instability.

scholarly journals On the SuperDARN cross polar cap potential saturation effect

2009 ◽  
Vol 27 (10) ◽  
pp. 3755-3764 ◽  
Author(s):  
A. V. Koustov ◽  
G. Ya. Khachikjan ◽  
R. A. Makarevich ◽  
C. Bryant
Keyword(s):  
Electric Field ◽  
Linear Trend ◽  
Limited Data ◽  
Polar Cap ◽  
Data Set ◽  
Northern Summer ◽  
Radar Network ◽  
Cross Polar Cap Potential ◽  
Hemisphere Winter ◽  
Magnetic Index

Abstract. Variation of the cross polar cap potential (CPCP) with the interplanetary electric field (IEF), the merging electric field EKL, the Polar Cap North (PCN) magnetic index, and the solar wind-magnetosphere coupling function EC of Newell et al. (2007) is investigated by considering convection data collected by the Super Dual Auroral Radar Network (SuperDARN) in the Northern Hemisphere. Winter and summer observations are considered separately. All variations considered show close to linear trend at small values of the parameters and tendency for the saturation at large values. The threshold values starting from which the non-linearity was evident were estimated to be IEF*~EKL*~3 mV/m, PCN*~3–4, and EC*~1.5×104. The data indicate that saturation starts at larger values of the above parameters and reaches larger (up to 10 kV) saturation levels during summer. Conclusions are supported by a limited data set of simultaneous SuperDARN observations in the Northern (summer) and Southern (winter) Hemispheres. It is argued that the SuperDARN CPCP saturation levels and the thresholds for the non-linearity to be seen are affected by the method of the CPCP estimates.

scholarly journals Relationship between the Northern Hemisphere Joule heating and geomagnetic activity in the southern polar cap

2000 ◽  
Vol 105 (A12) ◽  
pp. 27167-27177 ◽  
Author(s):  
P. Ballatore ◽  
L. J. Lanzerotti ◽  
G. Lu ◽  
D. J. Knipp
Keyword(s):  
Northern Hemisphere ◽  
Geomagnetic Activity ◽  
Joule Heating ◽  
Polar Cap

scholarly journals Effects of the solar wind electric field and ionospheric conductance on the cross polar cap potential: Results of global MHD modeling

2003 ◽  
Vol 30 (23) ◽  
pp. n/a-n/a ◽  
Author(s):  
V. G. Merkine ◽  
K. Papadopoulos ◽  
G. Milikh ◽  
A. S. Sharma ◽  
X. Shao ◽  
...  
Keyword(s):  
Solar Wind ◽  
Electric Field ◽  
Polar Cap ◽  
Mhd Modeling ◽  
The Cross ◽  
Cross Polar Cap Potential
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